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<?php |
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declare(strict_types=1); |
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namespace Phpgeo\Processor\Polyline; |
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use Phpgeo\Bearing\BearingEllipsoidal; |
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use Phpgeo\Polyline; |
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/** |
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* Simplify Polyline. |
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* |
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* @author Marcus Jaschen <[email protected]> |
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*/ |
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class SimplifyBearing implements SimplifyInterface |
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{ |
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/** |
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* @var float |
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*/ |
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private $bearingAngle; |
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/** |
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* SimplifyBearing constructor. |
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* |
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* @param float $bearingAngle |
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*/ |
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public function __construct(float $bearingAngle) |
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{ |
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$this->bearingAngle = $bearingAngle; |
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} |
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/** |
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* Simplifies the given polyline |
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* |
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* 1. calculate the bearing angle between the first two points p1 and p2: b1 |
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* 2. calculate the bearing angle between the next two points p2 and p3: b2 |
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* 3. calculate the difference between b1 and b2: deltaB; if deltaB is |
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* smaller than the threshold angle, remove the middle point p2 |
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* 4. start again at (1.) as long as the polyline contains more points |
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* |
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* @param Polyline $polyline |
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* |
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* @return Polyline |
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*/ |
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public function simplify(Polyline $polyline): Polyline |
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{ |
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$counterPoints = $polyline->getNumberOfPoints(); |
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if ($counterPoints < 3) { |
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return clone $polyline; |
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} |
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$result = new Polyline(); |
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$bearingCalc = new BearingEllipsoidal(); |
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$points = $polyline->getPoints(); |
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$index = 0; |
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// add the first point to the resulting polyline |
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$result->addPoint($points[$index]); |
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do { |
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$index++; |
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// preserve the last point of the original polyline |
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if ($index === ($counterPoints - 1)) { |
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$result->addPoint($points[$index]); |
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break; |
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} |
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$bearing1 = $bearingCalc->calculateBearing($points[$index - 1], $points[$index]); |
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$bearing2 = $bearingCalc->calculateBearing($points[$index], $points[$index + 1]); |
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$bearingDifference = min( |
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fmod($bearing1 - $bearing2 + 360, 360), |
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fmod($bearing2 - $bearing1 + 360, 360) |
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); |
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if ($bearingDifference > $this->bearingAngle) { |
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$result->addPoint($points[$index]); |
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} |
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} while ($index < $counterPoints); |
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return $result; |
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} |
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} |
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